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A New Protein Reduction System for Latex Glove Manufacturing – Bioblox™ MARGMA International Rubber Glove Conference, 12 – 14 September 2006 By Rick Tabor, Research Associate; Stepan Company (USA) and Bill Howe, PolyTech Synergies LLC. (USA)

IntroduIntroduIntroduIntroductionctionctionction

The topic of protein reduction for latex gloves and other articles comprised of

NR latex is no stranger to manufacturers of these products. Research

continues in efforts to reduce protein levels by double centrifuging, or through

additives to the latex concentrate at the plantation level prior to shipment to

the manufacturing plant. In all cases known thus far, the cost of NR latex raw

material increases commensurately with the cost of the additional processes

and/or materials required to demonstrate benefit by these products for

manufacturers seeking lower protein levels.

In the 1990’s, a slip coating was first introduced to replace powder as a glove

donning agent. Today, the growth of powderfree gloves by polymer coating

method continues, along with the steady presence of powdered gloves. For

these products, manufacturers continue to welcome methods to further reduce

protein levels in latex gloves. Post process chlorinated gloves were not

targeted for this study, in that most of this product family benefits from

significant protein reduction afforded by the exposure to chlorination and

downstream post washing.

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The standard method for lowering protein for the targeted product family of

this study (powdered gloves and polymer coated gloves) is that of longer

leaching times and/or higher leaching temperatures, sometimes as high as 70

degrees Celsius. That technique for continues today in many manufacturing

plants, and adds cost primarily through energy consumption and water

consumption.

The intent of this study was to develop an on-line leach tank protein reduction

additive that would seamlessly be implemented within most existing glove

manufacturing plants for powdered latex gloves and polymer coated latex

gloves. The goal is to achieve the following:

1. Result in no compromise to physical properties of the latex film.

2. Be environmentally safe and be compatible with existing post water

treatment plants.

3. Add no cost, or even possibly decrease manufacturing cost of the latex

article. To achieve this, the modest cost of the additive would need to be

offset by reduced leaching times, lower operating temperatures in the

leaching system, or other yet unidentified savings.

4. Add little or no cost to manufacturing lines in the way of additional

equipment and/or modification to existing lines.

5. Result in impressive reduction of extractable proteins of latex articles, in

tandem with objectives one through four above.

The PremiseThe PremiseThe PremiseThe Premise

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The washing of articles, regardless of material composition, is a long standing

method of removing contaminants and restoring articles as close as possible to

their original state of cleanliness. To optimize the washing of clothing, for

example, one would employ the use of a detergent that contains certain

surfactants to assist in removal of stains caused by many outside factors. The

stains are effectively loosened and released from the fabric in tandem with

detergent washing followed by water rinsing to remove the stains along with

any residual cleaning agents. Residential laundry detergents are

environmentally safe, of course, posing no hazard to water treatment plants or

the community in general.

In turn, the objective of this study was to test introduction

of certain surfactants into the leaching process for latex

gloves that would in turn result in enhance or accelerate

removal of extractable proteins in latex films, especially

gloves. Unlike detergents used for washing clothes, the

combination of ingredients used for latex glove

manufacturing applications would need to keep foaming non-existent or kept

at least to minimum levels controllable by industry de-foaming aids.

Testing Parameters and ProtocolTesting Parameters and ProtocolTesting Parameters and ProtocolTesting Parameters and Protocol

Protocol used for testing was:

1. The Standard Malaysian Glove Program, which cites

targeted maximum allowable protein levels in

powdered gloves of 200 mg/dm2.

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2. ASTM D3578, which cites targeted maximum

allowable protein levels in powdered gloves of 200

mg/dm2.

In turn, to ensure measurable and accurate detection, the “Control” target for

subsequent testing was determined to be 200 mg/g or approximately 300

mg/dm2 (Modified Lowry method).

Testing was conducted using the following independent laboratories and

associated testing regimen:

Testing MethodTesting MethodTesting MethodTesting Method Lab / LocationLab / LocationLab / LocationLab / Location

ASTM D5712-95 Modified Lowry Leap Testing Service, USA

ASTM D6499-03 Inhibition ELISA Leap Testing Service, USA

FITkit® Quattromed Ltd., Estonia

Product made for Protein Testing Purposes: Examination Glove

Latex Used: Pre-vulcanized Thai latex compounded by Killian Latex; Akron,

Ohio USA.

Coagulant: Water based with 20% calcium nitrate, wetting agents, and release

agent.

Leach water: Salem, Ohio City Water and de-ionized water by reverse osmosis.

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Dip Machine: DipTech Systems Diplomat™ Computerized Pilot Plant

Diplomat Pilot Plant Finished Gloves before stripping

The initial repeatable glove manufacturing process employed was as follows:

1. Clean Mold with warm water

2. Coag Dip – 1 ips entry / 5 seconds dwell / 2 ips exit

3. Coag Dry – 1 minute with rotation and heated convection

4. Latex Dip – 1 ips entry / dwell 9 seconds / 2 ips exit

5. Air dry 60 seconds

6. Pre Oven Leach – 3 minutes @ 54 degrees C (time and

temperature later reduced)

7. Oven Dry – 1 minute at 80 degrees C

8. Bead roll by hand

9. Cure – 13 minutes at 100 degrees C / 2 minutes - 110 degrees C

10. Post leach – 2 minutes @ 54 degrees C (later reduced)

11. Oven Dry – 2 minutes at 70 degrees C.

12. Cool Down – 2 minutes ambient

13. Powder by hand

14. Strip (hand protection – disposable nitrile gloves)

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Bioblox™ Concentration in Leach Water: 0.5% Active Ingredient finalized after

testing levels at 0.25%, 0.5%, and 1.0% Active Ingredient.

Testing HistoryTesting HistoryTesting HistoryTesting History

Round one of testing showed that “control” levels of protein in gloves, using

the Modified Lowry method were undetectable (less than 28 mg/g or less than

41 mg/dm2). It was determined that the use of Salem, Ohio city water for

leaching was introducing bias into the study model. This water had chlorine

present through addition at the city water treatment plant. Therefore,

subsequent iterations were switched to de-ionized water through reverse

osmosis process to remove ingredients influencing the study results.

Round two’s testing resulted in similar results of below detectable limits for

“control”; this after water temperature was reduced to 38 degrees Celsius for

this round of testing.

Round three focused on centering in on proper “control” standards against

which Bioblox™ treatment would be measured. Leach temperatures were set

to 38 degrees C. Results from the laboratory were as follows:

Lab Iteration Pre Leach Post Leach Protein

mg/g

Protein

mg/dm2

M 30 seconds 15 seconds 105 169

N 0 seconds 30 seconds 729 1052

O 30 seconds 30 seconds 237 366

P 180 seconds 30 seconds 33 52

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Testing for Round 4 was established with pre-oven leach residence time as 30

seconds and post leach residence time of 15 seconds, in accordance with

Group M in the previous round (that closest to the SMG standard of 200

mg/dm2). Five different grades of Bioblox™ surfactant treatment were tested

against control. For Bioblox™ treatment, both pre-oven leaching and post-

oven leaching residence times of 30 seconds and 15 seconds respectively,

were subjected to 100% exposure to Bioblox™ additive at 0.5% active

ingredient to water. No residual rinse for either step was employed. Results

demonstrated that the process established for this round actually increased

protein content against “control”.

Round 4 ResultsRound 4 ResultsRound 4 ResultsRound 4 Results

Group ID Additive Lowry mg/g Lowry

mg/dm2

ELISA

mg/dm2

Q Control 351 538 9.3

R Bioblox L 546 906 18.9

S Bioblox A 561 879 47.9

T Bioblox S 402 634 13.7

U Bioblox M 534 854 13.7

V Bioblox 460 360 568 10.9

Corrections instituted for Round 5:

• Increased post oven leaching residence time from 15 seconds to 45

seconds, and split post leaching to 20 seconds water only, followed by

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25 seconds Bioblox treatment. Pre Oven leach of 30 seconds of Bioblox

treatment only continued.

Round 5 resulted in the first improvement in protein levels against the

“control” iteration. The best Bioblox bath resulted in a total overall protein

reduction of about 20% - effective, but not considered impressive enough to

warrant pursuit of production plant testing at that time. Rounds 6 and 7

focused on establishing the proper level of Bioblox concentration, testing

various routines at both 0.5% and 1.0% active ingredient to water. This test

overwhelmingly determined that the higher concentration of Bioblox™ did not

benefit protein reduction according to the laboratory data, and that the level of

0.5% active ingredient appeared effective against protein removal. This proved

to be a key statistic in the interest of keeping any material cost addition to the

process, low.

Testing continued on various grades of Bioblox™ through testing rounds 8, 9

and 10, including adjusting the leach water pH to determine if this had an

impact on enhancing protein removal in tandem with Bioblox™. For all

iterations, it was determined that normal water pH levels of 6.5 to 7.0 was the

optimal level for Bioblox™ performance. When pH was raised (to

approximately 12) or lowered (to approximately 3.2), the protein levels

increased anywhere from 10% to 30%, from that of regular water pH levels.

Round 11 yielded the most compelling results for protein removal, with the

following major process change implemented for testing, which resulted in

compelling protein reduction for several Bioblox™ versions:

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Many glove lines have 3 or more separate leach tanks for both pre oven and

post oven leaching. Earlier results showed that Bioblox performed at a higher

level by first exposing the glove to water only, before entering the Bioblox™

treatment stage. However, in no earlier testing was a residual water rinse

subjected to the glove after the Bioblox™ exposure.

For Round 11, the following leaching schedule was implemented, with all

water temperatures remaining at 38 degrees C.

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Station Leach H20

only

Bioblox™ Leach H20

only

Total Leach

Pre Oven

Leach

10 seconds 15 seconds 10 seconds 35 seconds

Post Oven

Leach

15 seconds 20 seconds 10 seconds 45 seconds

Testing for Round 11 yielded favorable protein reduction results as follows:

Group IDGroup IDGroup IDGroup ID AdditiveAdditiveAdditiveAdditive Lowry Lowry Lowry Lowry

mg/gmg/gmg/gmg/g

Lowry Lowry Lowry Lowry

mg/dm2mg/dm2mg/dm2mg/dm2

ELISA ELISA ELISA ELISA

mg/gmg/gmg/gmg/g

ELISA ELISA ELISA ELISA

mg/dm2mg/dm2mg/dm2mg/dm2

QQQ Control 215 332 2.9 4.4

RRR Bioblox

3198

135 212 1.4 2.2

SSS Bioblox

FA

65656565 106106106106 0.50.50.50.5 0.70.70.70.7

TTT Bioblox F 95 150 1.6 2.4

All Bioblox treatments benefited and improved in lab results by employment

of a short residual water rinse after 0.5% concentration Bioblox™ treatment in

the prior leach tank, preceded by another “water only” tank.

It was perceived that the potential for Bioblox™ as a protein treatment was

commercially viable, meeting all of the project objectives established during

early testing in 2005.

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To further validate protein reduction potential of Bioblox™, samples consistent

with the leaching process in Round 11 (water – Bioblox™ - water) were made

at the pilot plant, and sent for FITkit® analysisFITkit® analysisFITkit® analysisFITkit® analysis. These highly sensitive tests use

specific monoclonal antibodies developed against the four major latex

allergens (Hev b 1, Hev b 3, Hev b 5 & Hev b 6.02) known to be present in NRL

products.

Group IDGroup IDGroup IDGroup ID AdditiveAdditiveAdditiveAdditive Hev b 1Hev b 1Hev b 1Hev b 1 Hev b 3Hev b 3Hev b 3Hev b 3 Hev b 5Hev b 5Hev b 5Hev b 5 Hev b 6.02Hev b 6.02Hev b 6.02Hev b 6.02

NNNN Bioblox

NF

Undect. Undect. 0.09 0.15

OOOO Bioblox

FA

Undect. Undect. 0.1 0.18

PPPP Control Undect. Undect. 0.24 0.48

QQQQ Bioblox L Undect. Undect. 0.04 0.08

RRRR Bioblox

3198

Undect. Undect. 0.24 0.28

Further testing was conducted in 2006 at a few manufacturing locations in

Malaysia, yielding promising results. In one test, a “control” was implemented

using normal Malaysian leach water and process temperatures of 60 degrees

C. A total of 60 seconds of both Pre-oven leach and post oven leach was

employed for the test.

The Bioblox treatment, employed at 38 degrees C, demonstrated a reduction of

approximately 10% to 15% in protein levels compared against “water only

leaching” at typical elevated temperatures of 60 degrees C. This test

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demonstrated potential to achieve protein reduction better than existing

methods, while conserving energy costs so vital to profitability.

Equipment Equipment Equipment Equipment ImplementationImplementationImplementationImplementation

Bioblox™ in concentrate form is a liquid. Any dipping lines containing

approximately 30 to 45 seconds pre-oven and post-oven leaching are

candidates for simple installation of equipment necessary to implement the

system on existing lines. The following is one suggested procedure:

For example, in the case of BiobloxBiobloxBiobloxBiobloxTMTMTMTM LLLL, which is a 30% actives concentrate, the

dosage rate would be 0.005X1000/0.3 = 16.67 mls of Bioblox™ L Bioblox™ L Bioblox™ L Bioblox™ L per liter of

leach water.

This dosage level can be routinely controlled in leaching systems that drain

continuously, by addition of a metering pump connected to a Bioblox™Bioblox™Bioblox™Bioblox™

holding tank or shipping drum (See Figures 1 and 2 below), or by gravity feed

using a flexible feeding tube pinch system, metered via measured feed. Some

Bioblox™Bioblox™Bioblox™Bioblox™ grades are more viscous by nature, which may require a metering

pump system for best performance.

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Figure 1: EXAMPLE OF METERING PUMP FOR BIOBLOX™ (reference: Figure 1: EXAMPLE OF METERING PUMP FOR BIOBLOX™ (reference: Figure 1: EXAMPLE OF METERING PUMP FOR BIOBLOX™ (reference: Figure 1: EXAMPLE OF METERING PUMP FOR BIOBLOX™ (reference: www.dosatron.com)www.dosatron.com)www.dosatron.com)www.dosatron.com)

Figure 2: INSTALLATION OF METERING PUMP WITH BYFigure 2: INSTALLATION OF METERING PUMP WITH BYFigure 2: INSTALLATION OF METERING PUMP WITH BYFigure 2: INSTALLATION OF METERING PUMP WITH BY----PASSPASSPASSPASS Bioblox™Bioblox™Bioblox™Bioblox™ is best used when employed in both pre-cure oven leaching and

post-cure oven leaching systems. Best results are obtained by subjecting the

in-process latex article to the following leaching schedule for pre-oven and

post-oven leaching systems:

• First Stage Leaching – water only

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• Second Stage Leaching – Bioblox™ treatment in water

• Third Stage Leaching – water only (residual rinse)

Residence times for each leaching stage may vary according to the

manufacturer’s process and formulation, but the following minimal guideline

may be used for initial trials and validation:

• First stage leaching in water only – 15 seconds or more

• Second stage leaching in water with Bioblox™ - 15 to 20 seconds or

more

• Third stage leaching in water only – 15 seconds or more

It is possible that overall leach tank residence time may reduce from current

manufacturer settings. Each manufacturer must make this determination

based upon his/her evaluation and merit.

If one pumps water from the last leach tank upstream to the first leach tank, it

is important to by pass the Bioblox™ treatment tank with this procedure. The

Bioblox™ tank is best planned as an isolated leach tank with its own incoming

water line, and any overflow going to drain, not another leach tank. This is a

necessary approach, as protein reduction will likely suffer if Bioblox overflow

migrates to any upstream leach tank.

Future TestingFuture TestingFuture TestingFuture Testing

The following studies are planned for Bioblox™ treatment in the upcoming

months:

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1. Potential to remove vulcanization residues for both NR latex and nitrile

gloves.

2. Post process laundering benefits of Bioblox™ and impact on residual

removal and proteins.

3. More detailed study on protein removal of polymer coated latex gloves.

4. Extended wear testing.

5. Physical parameters testing.

6. Optimization of Bioblox™ using cost-benefit analysis through

concentration comparisons, saturated leach tank protein testing.